Small diameter dual lumen catheter

ABSTRACT

A multiple lumen catheter ( 110,150 ) having at least first and second lumens ( 112,114; 152,154 ). At least one of the first and second lumens ( 112,152 ) is generally C-shaped in cross-section, with a septum wall ( 120,160 ) dividing the first and second lumens providing a generally straight side to the C-shaped cross-section. A stylet or guide wire ( 130 ) may be disposed along the C-shaped cross-section lumen ( 112,152,154 ) having a larger diameter than one used with catheters of the same outer diameter but that have lumens of only D-shaped or circular shaped cross-sections.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplication Ser. No. 60/931,916 filed May 25, 2007.

FIELD OF THE INVENTION

This invention relates to the field of medical devices, and moreparticularly to implantable catheters such as for infusion andhemodialysis.

BACKGROUND OF THE INVENTION

Catheter assemblies, and particularly catheter assemblies for use inhemodialysis, are known that have one, two or more lumens extending froma distal end to a proximal end, where the distal end is placed in ablood vessel of a patient, such as the jugular vein, with the proximalend extending from the patient for each lumen to be connected to arespective conduit of a hemodialysis machine. Customarily, each lumen ofthe catheter assembly is first connected to a respective extension tubewithin a hub body, and the extension tube is terminated in a luerconnector to facilitate connection with and disconnection from theconduit of the hemodialysis machine and commonly the extension tube hasdisposed therealong a clamp, such as a Roberts clamp, for temporarilyclosing the conduit when necessary. Implanted catheter assemblies areconnected to medical apparatus such as hemodialysis apparatus throughthe luer connectors, and then disconnected therefrom, all through manycycles; such connection and disconnection involves the catheter assemblyundergoing many cycles of stress and strain especially focused at theproximal end where the catheter proximal end enters the hub whichconnects the catheter lumens to respective extension tubes, or where asingle lumen catheter enters its luer connector directly instead of viaa hub and extension tube.

It is desired to provide an assurance against occluding or kinking ofthe catheter lumens, as well as greater strength, at the connection ofthe catheter and the hub, or at the connection of a single lumencatheter luer connection where no hub is utilized.

Certain catheter assemblies, termed PICC catheters (for peripherallyinserted central catheters), are implanted through a vessel entry on anarm of the patient, known as axillary placement. But, usually, thecatheter assembly is secured to the torso of the patient in a manner toprevent any dislocation of the distal tips of the catheter lumens fromany movement along the vessel after initial placement at thecatheterization site. This manner of securement is usually accomplishedby a process termed tunneling, in which the proximal portion of thecatheter assembly outside of the vessel is tunneled subcutaneously nearthe vessel entry site, typically beneath the clavicle of the patient,whereafter the hub is sutured or otherwise secured to the patient. Bythis process, during the connection with and disconnection from thehemodialysis machine of the extension tubes, there is no stress orstrain passed to the distal end of the catheter assembly that might tendto dislodge the distal lumen tips from the desired location along thevessel.

The orientation of the tunneled portion of the catheter assembly is notaxially aligned with the distal portion of the catheter assembly and infact a relatively sharp bend may be made in the catheter assemblydistally of the tunneled portion during placement.

Catheters are conventionally produced in various sizes depending ondesired uses, and their outer diameters are measured in units termed“french” or “F”, with one F equaling 0.013 inches or 0.32 millimeters.The largest sized catheters utilized for vascular placement may have anouter diameter of about 17 F, and range to smaller sizes. Diameters of 5F are the smallest sized dual-lumen catheters that are presentlypreferred in that they present little difficulty with insertiontherethrough of small wires or stylets, or that have sufficient strengthand thus less kink susceptibility. Even smaller sized catheters areknown, however (4 F or less), such as are used with small adolescentsand adults. When the catheter outer diameter is almost the same size asthe inner diameter of the vessel within which it is implanted, certainproblems are associated with catheters after they are vascularly in apatient; for example, development of phlebitis and thrombosis is knownin such situations.

It is desired to provide a catheter with a very small outer diameter,especially a dual lumen catheter, thereby minimizing the tendency ofphlebitis or thrombosis or the like, to develop. Such a small diametercatheter is disclosed in U.S. Patent Publication No. US 2006/0206094 A1,which provides a catheter assembly wherein the catheter outer diameteris enlarged for at least some of its length proximate the proximal endadjacent the hub, relative to the remainder of the catheter extending tothe distal end. The inner diameter of the lumen or lumens remainsconstant; in a dual-lumen catheter, the inner septum wall between thelumens may also increase in thickness. A very small diameter dual lumencatheter (2.6 F) disclosed in the application provides two circularlumens each with a very small diameter of about 0.011 in (0.028 mm),sufficiently large for an 0.009 inch guide wire (0.23 mm) or 18 GA, andwhich is less likely to induce phlebitis, thrombosis or the like afterimplantation. This very small diameter catheter also benefits from anenlarged proximal end diameter, for resistance to occlusion and kinking.The use of stylets with catheters provides rigidity to the catheterduring insertion of the catheter into the patient. The catheter couldalso be inserted over a guide wire, where the guide wire too wouldprovide rigidity and guidance into and through the vasculature.

It is desired to provide a small diameter catheter suitable for use withstylets or guide wires that provide a sufficiently great level ofrigidity to the small diameter catheter during patient placement.

BRIEF SUMMARY OF THE INVENTION

The present invention is a small diameter multiple lumen catheter,wherein at least one of the lumens is adapted to receive therethrough astylet or guide wire. In one embodiment, for a dual lumen catheter, thecross-sectional shape of at least one lumen is generally C-shaped, withthe septum defining a straight side to the C-shape. The C-shapedcross-section maximizes lumen height enabling use of relatively largerdiameter stylets or guide wires. If the other lumen remains D-shaped,then the septum is offset from the axis in the direction toward theD-shaped lumen. In another embodiment, the cross-sectional shapes ofboth lumens are generally C-shaped, thus providing greater outer wallthickness at both sides of the septum that separates the lumens fromeach other.

The modified lumen cross-sectional shapes of the present inventionprovide for lumens of small double lumen catheters having a maximizedheight that allow for use of a relatively large stylet or guide wirewith such catheters than known small diameter catheters, that is, astylet or guide wire that is up to 30% larger than is able to be usedwith prior art lumens of small diameter dual lumen catheters. Use of oneof the fluid flow lumens for insertion of a stylet or guide wire, ofcourse, eliminates the need for the catheter to have a separate lumenfor the stylet or guide wire, thus enabling the catheter to have aminimized outer diameter. Further, the lumen design provides more lumenstability than comparable designs, to help prevent catheter kinking.Also, the lumen design provides increased tensile strength by increasingthe material cross-sectional area (by about 25%) when compared to theprior art double-D cross-sectional configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate the presently preferredembodiments of the invention, and, together with the general descriptiongiven above and the detailed description given below, serve to explainthe features of the invention. In the drawings:

FIG. 1 is a cross-sectional view of a PRIOR ART small diameter catheter,wherein the lumen cross-sectional shape is D-shaped, with a guide wireseen disposed along one lumen;

FIG. 2 is a cross-sectional view of a PRIOR ART small diameter catheter,wherein the lumen cross-sectional shape is circular, again with a guidewire seen disposed along one lumen;

FIG. 3 is a cross-sectional view of a first embodiment of catheter ofthe present invention;

FIG. 4 is a cross-sectional view of the catheter of FIG. 3 wherein astylet is emplaced in the C-shaped lumen; and

FIG. 5 is a cross-sectional view of a second embodiment of catheter ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the drawings, like numerals indicate like elements throughout.Certain terminology is used herein for convenience only and is not to betaken as a limitation on the present invention. The terminology includesthe words specifically mentioned, derivatives thereof and words ofsimilar import. The embodiments illustrated below are not intended to beexhaustive or to limit the invention to the precise form disclosed.These embodiments are chosen and described to best explain the principleof the invention and its application and practical use and to enableothers skilled in the art to best utilize the invention.

In FIG. 1, the prior art dual lumen catheter 10 is shown to have twolumens 12,14 each of which has a D-shaped cross-sectional shape, andshown in one lumen 12 is a guide wire 16. Exemplary dimensions for thecatheter 10 are: a French size of 2.6 F (about 0.035 in or 0.89 mm); theheight of lumen 12 or 14 is about 0.011 in (0.028 mm); and the minimumthickness of the septum is 0.004 in (0.10 mm). The diameter of guidewire 16 capable of fitting within and along lumen 12 is 0.009 in (0.23mm), or 18 GA. In this arrangement, because of vasculature bends, theguide wire easily is urged into the confined corners of the D-shapedlumen thus greatly increasing the frictional resistance to moving thecatheter relatively along the guide wire and increasing the difficultyfor the practitioner.

In FIG. 2, the prior art dual lumen catheter 50 is shown to have twolumens 52,54 each of which has a circular cross-sectional shape, andshown in one lumen 52 is a guide wire 56. Exemplary dimensions for thecatheter 50 are a French size of 2.6 F (the same as that of the priorart catheter of FIG. 1; the height of lumen 52 or 54 (i.e., the criticaldimension) is about 0.012 in (0.30 mm); and the septum thickness isabout 0.003 in (0.08 mm). The diameter of guide wire 56 capable offitting within and along lumen 12 is 0.009 in (0.23 mm), or 18 GA.

The present invention is shown in a first embodiment of dual lumencatheter 110 in FIGS. 3 and 4. Catheter 110 has a diameter of 2.6French, the same as the diameters of the prior art catheters of FIGS. 1and 2 for enabling meaningful comparison. A first lumen 112 is shown tohave a generally C-shaped cross-sectional shape, while the second lumen114 is D-shaped in cross-section. It is seen in FIGS. 3 and 4 that firstlumen 112 includes one straight side wall, defined by one side of septum120, while the remaining side walls are arcuate, circumscribing an arcof greater than 180°, the first lumen thus being C-shaped incross-section. Septum 120 is seen to be offset from the center of thecross-section toward the second lumen 114. The dimensions of first lumen112 has a width taken parallel to the septum, of 0.020 in (0.51 mm) anda height taken orthogonally to the septum (the critical dimension), of0.015 in (0.38 mm). In FIG. 4, a stylet 130 is disposed in first lumen112. The stylet 130 may have a diameter of up to 0.013 in (0.33 mm) andthus is larger than the stylet or guide wire possible to be used in theprior art catheters of FIGS. 1 and 2 even though the outer diameter ofthe catheter is the same.

In FIG. 5, dual lumen catheter 150 has a diameter of 3 French andincludes two lumens 152, 154 each of which is generally C-shaped. Thefirst and second lumens each have cross-sectional configurations thatare the same as first lumen 112 of FIGS. 3 and 4, with a septum 160separating lumens 152,154 from each other. Each of lumens 152,154 are ofsufficient size to accept therethrough a stylet or guide wire of up to0.014 in (0.36 mm) in diameter. Side walls 156,158 at ends of septum 160are seen to be thickened compared to the thickness of the outer walls atother locations about the catheter's circumference, thus enhancing thestrength of the catheter and enhancing the resistance to catheterkinking, and the lumens have no confined corners for frictionallygripping the relatively smaller stylet or guide wire as in the prior artcatheter lumen D-shaped cross-sections.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

What is claimed is:
 1. A multiple lumen catheter for use in fluidtransmission to and from a patient's vasculature, comprising: a catheterhaving a cross-section that is circular with a diameter of less than 5French, the catheter having at least first and second lumens separatedby a septum, wherein the septum defines a continuous straight side tothe first lumen while the remaining sides thereof are arcuate defining asubstantially constant-radius arc of greater than 180°, whereby thefirst lumen's height orthogonal to the septum is maximized enablingreceipt therethrough of a comparably larger stylet or guide wire, andthe catheter walls at laterally opposite ends of the septum are enlargedin cross-sectional area relative to catheter walls at locationsorthogonal to the septum, thereby minimizing catheter kinking orthogonalto the orientation of the septum.
 2. The multiple lumen catheter as setforth in claim 1, wherein the catheter is a dual lumen catheter.
 3. Themultiple lumen catheter as set forth in claim 2, wherein the septum alsodefines a continuous straight side to the second lumen cross-sectionwith the remaining sides thereof being arcuate defining a substantiallyconstant-radius arc of greater than 180°, whereby the lumen height ofeach lumen is maximized and the catheter walls at laterally oppositeends of the septum are enlarged in cross-sectional area relative tocatheter walls at locations orthogonal to the septum, thereby minimizingcatheter kinking orthogonal to the orientation of the septum.
 4. Themultiple lumen catheter as set forth in claim 3, wherein the septumdefines a continuous straight side to the second lumen.